A5076810820- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Magnetic Properties and Applications
- Characterization and Applications of Magnetic Nanoparticles
- ZnO doping and properties
- Advanced Memory and Neural Computing
- Magnetic and transport properties of perovskites and related materials
- Theoretical and Computational Physics
- Quantum and electron transport phenomena
- Multiferroics and related materials
- 2D Materials and Applications
- Magnetic Field Sensors Techniques
- Metallic Glasses and Amorphous Alloys
- Advanced Materials and Mechanics
- Geomagnetism and Paleomagnetism Studies
- Magneto-Optical Properties and Applications
- Advanced Data Storage Technologies
- Neural Networks and Reservoir Computing
- Anodic Oxide Films and Nanostructures
- Magnetic Properties of Alloys
- Ferroelectric and Negative Capacitance Devices
- Modular Robots and Swarm Intelligence
- Heusler alloys: electronic and magnetic properties
- Structural Analysis and Optimization
- Vibration and Dynamic Analysis
Korea Research Institute of Standards and Science
2016-2025
Seoul National University
2009-2014
Abstract The recent discovery of room‐temperature ferromagnetism in 2D van der Waals (vdW) materials, such as Fe 3 GaTe 2 (FGaT), has garnered significant interest offering a robust platform for spintronic applications. Various fundamental operations essential the realization spintronics devices are experimentally confirmed using these materials at room temperature, current‐induced magnetization switching or tunneling magnetoresistance. Nevertheless, potential applications magnetic skyrmions...
We examine magnetic domain wall motion in metallic nanowires Pt-Co-Pt. Regardless of whether the is driven by either fields or current, all experimental data fall onto a single universal curve creep regime, implying that both motions belong to same universality class. This result contrast report on semiconductor (Ga,Mn)As exhibiting two different classes. Our finding signals possible existence yet other classes which go beyond present understanding statistical mechanics interfaces.
Abstract Unidirectional motion of magnetic domain walls is the key concept underlying next-generation domain-wall-mediated memory and logic devices. Such has been achieved either by injecting large electric currents into nanowires or employing domain-wall tension induced sophisticated structural modulation. Herein, we demonstrate a new scheme without any current injection This utilizes recently discovered chiral walls, which exhibit asymmetry in their speed with respect to fields. Because...
We examine the current-induced dynamics of a skyrmion that is subject to both structural and bulk inversion asymmetry. There arises hybrid type Dzyaloshinskii-Moriya interaction (DMI) which in form mixture interfacial DMIs. Examples include crystals with symmetry classes ${\mathrm{C}}_{n}$ as well magnetic multilayers composed ferromagnet noncentrosymmetric crystal nonmagnet strong spin-orbit coupling. As striking result, we find that, systems DMI, spin-orbit-torque-induced Hall angle...
Among two-dimensional (2D) layered van der Waals materials, ferromagnetic 2D materials can be useful for compact low-power spintronic applications. One promising candidate material is Fe3GeTe2 (FGT), which has a strong perpendicular magnetic anisotropy and relatively high Curie temperature. In this study, we confirmed that an oxide layer (O-FGT) naturally forms on top of exfoliated FGT antiferromagnetic coupling (AFC) exists between O-FGT layers. From first-principles calculation, formation...
Abstract One long-standing goal in the emerging neuromorphic field is to create a reliable neural network hardware implementation that has low energy consumption, while providing massively parallel computation. Although diverse oxide-based devices have made significant progress as artificial synaptic and neuronal components, these still need further optimization regarding linearity, symmetry, stability. Here, we present proof-of-concept experiment for integrated computing networks by...
Abstract Efficient current‐induced switching of perpendicular magnetization is an essential task in spintronics for realizing high‐performance information processing and storage device application. However, the spin‐orbit torque (SOT) by injection in‐plane polarized spins cannot deterministically switch ferromagnetic thin films with magnetic anisotropy (PMA) without additionally applied external field to break symmetry PMA. Considering difficulties applying localized area only within a...
Abstract The one-dimensional magnetic skyrmion motion induced by an electric current has attracted much interest because of its application potential in next-generation memory devices. Recently, the unidirectional large (20 μm diameter) bubbles with two-dimensional topology, driven oscillating field, also been demonstrated. For high-density devices, it is preferable to reduce size skyrmion. Here we show numerical simulation that a few tens nanometres can be high-frequency field oscillations,...
A magnetic skyrmion isusually refers to a twisted spin texture surrounded by uniformly aligned out-of-plane spinsin the background of magnetized state. The invariance conserves its topological charge under any continuous transformations textures, leads which represents robustness their against external perturbations, making it ideal use skyrmions as . Such behaviour is required for an information carriers. To date, most studies have been performedfocused on in perpendicularly systems, where...
Abstract The paradigm shift of information carriers from charge to spin has long been awaited in modern electronics. invention the spin‐information transistor is expected be an essential building block for future development spintronics. Here, a proof‐of‐concept experiment magnetic skyrmion working at room temperature, which never demonstrated experimentally, introduced. With spatially uniform control anisotropy, shape and topology when passing controlled area can maintained. findings will...
Abstract Efficient magnetization control is a central issue in magnetism and spintronics. Particularly, there are increasing demands for manipulation of magnetic states van der Waals (vdW) magnets with unconventional functionalities. However, the electrically induced phase transition between ferromagnetic‐to‐antiferromagnetic without external field yet to be demonstrated. Here, current‐induced vdW ferromagnet Fe 5 GeTe 2 reported. Based on magneto‐transport measurements theoretical analysis,...
We demonstrate here that the current-driven domain wall (DW) in two dimensions forms a ``facet'' roughness, distinctive to conventional self-affine roughness induced by magnetic field. Despite different universality classes of these roughnesses, both current- and field-driven DW speed follow same creep law only with opposite angular dependences. Such dependences result stable facet angle, from which single image can unambiguously quantify spin-transfer torque efficiency, an essential...
The skyrmion magnetic bubble in a ferromagnetic disk exhibits hypocycloidal gyrations contrary to the vortex gyration, showing simple circular trajectory. To describe mass term is needed Thiele's equation. In this study, we analytically derived both and spring constant term, which are crucial parameters for describing gyration. Values obtained by these analytic expressions were consistent with those simulations. We could find dependences of two terms on several external parameters, including...
Abstract The magnetic skyrmion is a topologically protected spin texture that has attracted much attention as promising information carrier because of its distinct features suitability for high‐density storage, low power consumption, and stability. One the devices proposed so far racetrack memory, which version domain‐wall memory. For application in devices, memory requires electrical generation, deletion, displacement isolated skyrmions. Despite progress experimental demonstrations...
Abstract Nonlinearity of dynamic systems plays a key role in neuromorphic computing, which is expected to reduce the ever-increasing power consumption machine learning and artificial intelligence applications. For spin waves (magnons), nonlinearity combined with phase coherence basis phenomena like Bose–Einstein condensation, frequency combs, pattern recognition computing. Yet, broadband electrical detection these high-frequency resolution remains challenge. Here, we demonstrate generation...
We report an experimental observation that indicates a direct relation exists between the speed of magnetic domain-wall (DW) motion and magnitude perpendicular anisotropy (PMA) in Pt/Co/Pt films. It is found by changing thicknesses nonmagnetic Pt layers, PMA can be varied significantly field-driven DW also modified factor up to 50 under same field. Interestingly, exhibits clear scaling behavior with respect magnitude. A theory based on creep criticality successfully explains observed...
We have found that the depinning field of domain walls (DWs) in permalloy (Ni81Fe19) nanowires can be experimentally controlled by interactions between magnetic stray fields and artificial constrictions. A pinning geometry consists a notch nanobar is considered, where DW traveling nanowire pinned with vertical to it. direction magnetization affects shape local energy minimum potential landscape experienced DW; therefore, strength strongly depends on interaction from external force notch. The...
Abstract Magnetic skyrmions, which are topological swirling spin textures, have drawn much attention in spintronics because of their use as an information carrier with distinct robustness rooted nature. Real-time generation skyrmions is therefore imperative for realizing skyrmion-based spintronic devices. However, to date, experimental demonstration has been limited exquisite works well-tuned samples. Here, we report a method generate by driving the stripe instability via in-plane magnetic...
Two distinct pinning mechanisms named as kinetic and static of magnetic domain wall (DW) are experimentally resolved. Both the situations realized at an artificial notch on U-shaped Permalloy nanowires, depending initial DW states, moving or pinned. The depinning field—a critical field for a to be trapped notch—is revealed distinguishably smaller than depin notch. Based one-dimensional collective model, discrepancy is explained by tilting angle DW.
A magnetometric technique for detecting the magnetic anisotropy field of ferromagnetic films is described. The based on extraordinary Hall voltage measurement with rotating film under an external field. By analyzing angle-dependent Stoner-Wohlfarth theory, uniquely determined. present pertinent especially ultrathin strong intrinsic signal, in contrast to conventional techniques which signal proportion sample volume and geometry.
We report an experimental detection of a long-range tension effect on magnetic domain walls in Pt/Co/Pt films. Such is observed from circular domains expanding (or shrinking) under constant applied field. Interestingly, the propagation speed varies with respect to radius. Converting variation field via creep scaling, it revealed that there exists effective inversely proportional radius, accordance wall and magnetostatic dipolar interaction. The sizeable subsists over 20 µm, providing way...
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Abstract The switching of magnetization via spin‐orbit torque has attracted much attention because its fast and low power consumption. Numerous studies have focused on increasing the conversion efficiency from charge to spin current out‐of‐plane cases. Recently, there been reports deterministic in‐plane devices. It is reported that an (SOT) device can archive oscillation, precession, direct by a combination torques—controlling thickness ferromagnet normal metal. With proper layer...